The invention is based on an electromagnet of the type defined hereinafter. An electromagnet of an electromagnetically actuatable valve having a built-in permanent magnet has already been proposed, in which in the non-excited state the armature is attracted to the core, while upon electromagnetic excitation the armature assumes a position spaced apart from the core. This kind of valve has the advantage of not requiring any holding current in the position of repose. However, because cylindrical and flat magnets are used, the valve is large in terms of its structural size.